Document Type : Article

Abstract

Abstract
144juvenileSobaity,Sparidentexhasta,afteracclimationtolaboratoryconditionsinseawater(40ppt)foroneweek,seawaterwasreplacedwithdifferentsalinities(5,20and60ppt)andseawater(40ppt)ascontrol.Samplingswereperformedat6and12hours,1,2,7and14daysafterthetimeofchanginginenvironmentalsalinities.Bloodsampleswerecollectedforplasmacortisol,glucoseandelectrolytesanalysis.Accordingtotheresults,plasmalevelsofcortisolshowedsignificantincreasesin5and60pptenvironmentinrelationtocontroland20pptgroups12hoursfromthebeginningoftheexperiment.Howeverin24hsamplesuptotheendoftheexperiment(14days)therewerenosignificantdifferencesamongtreatments.Plasmaglucoselevelsshowedasignificantincreaseonlyat12hsamplingtimeinrelationto6and24hoursinfishadaptedto5and60ppt.PlasmaCa⁺⁺concentrationshadnosignificantchangesduringexperiment.PlasmaMg⁺⁺amountsdecreasedsignificantlyin5and20pptgroupsinrelationwithcontrolat24hsamplingtime.Inconclusion,cortisolhasimportantroleinadaptationtoboth5and60pptatthebeginningoftheexposure,becauseofitssignificantincreaseatjust12hoursin5and60pptthanthecontrols,buttheroleofcortisolhasbeenreplacedwithotherchangesinosmoregulatoryrelatedtissuesandcellsaccordingtotheplasmacortisolamountsin5and60pptthatreturnedtothebasiclevels